The embodiments described herein relate generally to centrifugal fan assemblies, and more particularly, to centrifugal fan assemblies for use in forced air or air circulating systems.
Many known residential and commercial forced air, heating and air conditioning distribution systems require air propulsion units. In addition to providing movement of air for heating and cooling systems, air propulsion units are often used in combination with condenser units or to supplement other heat transfer operations. Some known air propulsion units are motor driven fans. These fans may be, for example, a centrifugal fan driven by an electric motor.
Centrifugal fans are known to be used to pressurize a rectangular cabinet with air for channeling to other components of the air distribution system. At least some known centrifugal fans include a plurality of blades that are in close proximity to a surface of the cabinet. During operation of at least some known centrifugal fans, the blades rotate about an axis to pull air into the fan in a direction parallel to the rotational axis. As the blades spin, the air is discharged between adjacent blades in a direction perpendicular to the axis of rotation. As such, when the air is discharged, it impinges upon the proximate perpendicular surface of the cabinet and is directed back toward the centrifugal fan. The impinging air may produce noise within the cabinet, any amount of which is objectionable by the user, and may cause a flow disruption with the air being discharged from the centrifugal fan. Any disruption in the airflow may cause a reduction in the overall efficiency of the fan. Moreover, the ejection of the air in a direction perpendicular to that which it entered the fan causes a significant momentum loss, which further reduces centrifugal fan efficiency